Elevator systems are widely known and used. Typical arrangements include an elevator cab that moves between landings in a building, for example, to transport passengers or cargo between different building levels. A motorized elevator machine moves a rope or belt assembly, which typically supports the weight of the cab, and moves the cab through a hoistway.
The elevator machine includes a machine shaft that is selectively rotationally driven by a motor. The machine shaft typically supports a sheave that rotates with the machine shaft. The ropes or belts are tracked through the sheave such that the elevator machine rotates the sheave in one direction to lower the cab and rotates the sheave in an opposite direction to raise the cab.
A rope or belt typically includes one or more tension members to support the weight of the elevator cab. These tension members may be encapsulated in a polymer jacket. One type of tension member comprises steel strands with a polymer jacket. The jacket surrounds the tension members and provides traction between the rope or belt and the sheave.
Conventional jacket application processes leave portions of the cords uncovered by the jacket material. One known technique includes depositing a zinc coating on the steel tension members to protect the exposed portions from corrosion that may result from exposure to the environment in a hoistway.
One disadvantage of typical jacketed ropes and belts may be insufficient adhesion between the polymer jacket and the tension members. The adhesion provides a “pull-out” strength to maintain a desired alignment of the tension members and the jacket. The adhesion also is responsible for transferring the weight of the elevator cab from the jacket to the steel cords. If the weight is not effectively transferred from the weaker jacket material to the stronger steel material, the jacket may be subjected to overstressing. The use of a zinc coating on the steel as mentioned above may further impair a desired level of adhesion.
Another disadvantage of typical ropes and belts may be frictional wear between the steel strands. As the rope or belt bends over a sheave, for example, the steel strands of a tension member may slide relative to each other and rub together. Repeated sliding may subject the steel strands to undesirable wear over a period of time. Conventional zinc coatings do little to reduce this problem.
There is a need for a rope or belt assembly that has improved adhesion between the tension members and the jacket. This invention addresses that need and provides enhanced capabilities while avoiding the shortcomings and drawbacks of the prior art.